The present invention relates to nuts, and particularly to an improved process for preparing defatted nuts to retain a greater proportion of their natural flavor.
The term "nuts" as used in this description includes whole nuts and pieces of nuts such as peanuts, almonds, Brazil nuts, filberts, pecans, walnuts, and the like. For purposes of conciseness in description, the following disclosure will center around the production of low-fat peanuts. It is not intended, however, to be limited to peanuts because the principles which will apply for peanuts should apply to other nuts.
The basic procedures for preparing partially-defatted nuts have been known for a number of years. For example, in U.S. Pat. Nos. 2,003,415 to Ammann and 3,294,549 to Vix et al, there are described procedures for pressing the oil from nuts such as peanuts. Broadly, these methods include the steps of pressing nuts until the desired quantity of oil is removed, and then steaming or cooking the partially-defatted nuts in water until the nuts are reconstituted to substantially their original size and shape. Both of these patents discuss the virtues of partially defatted nuts in the diet.
In U.S. Pat. No. 3,294,549, Vix et al indicate that the resulting high protein products have excellent flavor, aroma, taste, texture, and appearance, and good shelf life. They indicate that their process can be performed on raw, toasted, blanched or unblanched nuts with equivalent results; however, no example is directed to toasted nuts and there is no teaching or suggestion that pretoasted nuts, when properly processed, will be more flavorful. In fact, the various rehydration and drying procedures taught would negate any flavor benefit due to toasting prior to pressing. Further work on the Vix et al process is described in a series of articles entitled "Development and Potential of Partially Defatted Peanuts," Peanut Journal and Nut World, January and February 1967, and an article entitled "Low Calorie Peanuts", Food Processing/Marketing, September 1965.
Later workers, encouraged by the apparent appeal of products of that type to weight conscious consumers, continued to work in this area. Because the caloric density of fat is twice that of protein and carbohydrates, the removal of such a significant amount of fat from nut products could result in significant calorie reductions. Moreover, because these products were typically less dense than the normally treated non-defatted nuts, yet further calorie reductions were obtainable. In U.S. Pat. No. 3,645,752 to Baxley, there is disclosed a process which is said to improve the flavor of partially-defatted nuts by quenching them in a flavored oil after roasting. In U.S. Pat. No. 3,740,236, also to Baxley, it is indicated that the roasted peanut flavor appears to be reduced in proportion to the percentage of the peanut oil removed during the pressing process. Baxley, however, does not directly confront this flavor loss but provides a process for improving flavor of the nuts once the flavor is diminished. According to this patent, the defatted nuts are reconstituted in an aqueous binder solution which can also contain flavors.
Gannis et al, in U.S. Pat. No. 4,049,833, also recognized the adverse effect on the flavor and texture of partially-defatted nuts. To correct this, Gannis et al suggested contacting the partially-defatted nuts with a glycerol-containing solution during reconstitution, prior to roasting. They disclosed that after roasting, the treated nuts have improved flavor, texture and storage stability.
The exact reason for the flavor loss in the partially-defatted nuts is not fully understood. The Doctoral Dissertation of M. E. Mason entitled Procedures in Studying and Factors Influencing the Quality and Flavor of Roasted Peanuts, Oklahoma State University, 1963, pages 63 and 64, indicates that oil pressed from peanuts contain aleurone grains, among other particulates, which appear to contain flavor percursors. The Mason dissertation, however, was not concerned with the preparation of low-fat nuts, but simply gaining a better knowledge of the source and identification of flavor principals in peanuts.
Thus, while the prior art offers considerable promise to the producers and consumers of peanut and other nut products, by holding out opportunity for partially-defatted nut products, the prior art has not yet been able to produce a high quality product of this type. Flavor and texture problems remain. Particular problems persist in the assurance of natural nut flavor, without the need to cover up the lack of it by means of added flavorings and the like.